Art of compounding rubber



naphthenic acids themselves,

Patented July 2 1 19 31 1 NITED STATES.

PATENT-OFFICE ANSEL M. KINNEY, OF CHICAGO, ILLINOIS, ASSIGNOB TO STANDARD OIL COMPANY, OF

' WRITING, INDIANA, A CORPORATION OF INDIANA Anr or. comrounnmo RUBBER e,

11o Drawing.

The present invention relates to improve ments in the art of preparing'rubber com.- pounds and in the resulting compounds themselves, and will be fully understood from the following description thereof.

' I have found that the properties ofrubber compounds may be substantially improved, particularly with respect to durability, elongation and tensile strength by incorporatjo ing into such rubber compounds prior to vulcanization thereof, suitable proportionsof mineral oil naphthenic compounds. Such naphthenic compounds may be of two types; those present innaphthenic oils, such as the crude oils found in Louisiana, which com pounds are preferentially soluble in an alkaline solutionin the presence of the oil in whichthe occur and those naphthenic compounds, t e alkaline metal compounds of 2.0 of which are preferentially soluble in the oil in which they occur in the presence of water or an aqueous solution of. alkali. The former type may be desi ated as the preferentially water soluble nap thenic compounds, and the latter asthe preferentially oil soluble naphthenic compounds, Although both types of compounds ma be em loyed in carrying out the invention, have ound that the best results are secured by the use of the preferenao tially oil soluble type, and therefore refer to the same in the specific example hereinafter set forth.

- Although the alkali salts or other metallic salts of both types of naphthenic com ounds 35 may be employed, I prefer to emp 0y the may not be accompanied by some mineral oil without deleterious effect upon the rubber compound. I- may employ from 0.5 to 5 parts 4 of the naphthenic compound, and particularly naphthenic acids, per one hundred parts of rubber in the compound containing the usual compounding constituents, such as sulfur, zinc oxide, other fillers as desired, and accelerators. For example, ajspecific compound which I have prepared contains 100parts rolled brown rubber, 6 parts sulfur, 5 parts zinc oxide, 1 part accelerator and 2 parts of preferentially oil soluble naphthenic acid ac- 0 'companied by an approximately equivalent which may on Application filed May .6, 1926. Serial No. 107,286.

amount of oil, which latter I have found to have substantially no effect upon the properties of the resulting compound. Such a compound, suitably vulcanized, for example, for 30 to 90 minutes at 290 F., shows very 65 markedly improved properties over a similar compound from which the naphthenic acid is absent. F

It is readily apparent that the proportions of the compounding ingredients given above are merely illustrative and may bevaried within the knowledge of the rubber compounder. The naphthenic compounds may be supplied in any'desired way and in suitable proportions in -'any rubber compound prior to vulcanization, in accordance with my invention.

' I claim: i

1. A rubber compound containing rubber, vulcanizing constituents, and a substance se- 7 lected from the oup consisting of preferentially oil solub e naphthenic acids derived from mineral oils and thealkali metal salts of such acids. a 2. A rubber compound comprising rubber, vulcanizing constituents, and perferentially oil soluble naphthenic acids derived from mineral oils. v

3. A rubber compound comprising rubber,-

vulcanizi g constituents, and preferentially 89 oil solubl naphthenic acid in the ro rtion' of 0.5 to 5 parts per 100 parts 0 ru ber in the compound.

r 4. A rubber compound comprising rubber vulcanizing constituents, and preferentially from the group consisting of preferentially oil soluble naphthenic acid derived from 95 mineral oils and the alkali metal salts of such acid. V i

6. The method of preparing a rubber compound-which comprises incorporating therein prior to vulcanization a preferentially oil l l l l soluble naphthenic alcid derived from mineral oil.

7. The method of preparing a-rubber compound which comprises incorporating there- 5 m prior to vulcanization preferentially oil soluble naphthenic acid derived from mineral oil and free from metallic naphthenates and other naphthenic acid derivatives.

- ANSEL M.'KINNEY, 

